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41.
Thirty-four strains belonging to various species of the genus Thermus (T. aquaticus, "T. thermophilus,"
"T. brockianus,"
T. scotoductus, and genomic species 2) isolated from hot springs of different geographical areas were examined for plasmid content and restriction
fragment length polymorphism (RFLP) of plasmid DNAs. The four strains of the numerical taxonomy cluster E of genomic species
2 did not harbor plasmid DNA. Overall examination of the HindIII-RFLP profiling of plasmid DNA showed considerable variability between and within genomic species, with the exception
of presumed clonal isolates. In spite of this heterogeneity, HindIII plasmid digests within a numerical taxonomic cluster gave a subset of restriction fragments of similar or identical length.
Strains belonging to genomic species 2 or unclassified isolates from S. Pedro do Sul that harbored plasmid DNA (7 of the 14
strains studied) exhibited strong DNA homology between plasmid regions. No homologous sequences to these plasmid regions were
found in chromosomal DNA from strains isolated from S. Pedro do Sul in which no plasmids were detected. The strains belonging
to T. scotoductus formed two plasmid DNA homology groups, as estimated by probing with a plasmid fragment that coincided with the two numerical
taxonomy clusters proposed previously. Among the other species, homology of plasmid regions was also found between some strains.
Strong homology was also found between plasmid regions from some strains of different taxonomic groups, isolated from the
same and from different sources, suggesting that these sequences are highly conserved in plasmids present in Thermus. For plasmid-containing strains, results of plasmid RFLP profiling/DNA homology appear promising for the typing of Thermus at the level of biotypes or of individual strains, namely, for monitoring the diversity and frequency of isolates from a
particular hot spring.
Received: 24 October 1994 / Accepted: 6 March 1995 相似文献
42.
43.
Leandro Marciano Marra Cláudio Roberto Fonsêca Sousa Soares Silvia Maria de Oliveira Paulo Ademar Avelar Ferreira Bruno Lima Soares Renato de Fráguas Carvalho José Maria de Lima Fatima Maria de Souza Moreira 《Plant and Soil》2012,357(1-2):289-307
Introduction
In addition to fixing atmospheric nitrogen, some bacterial isolates can also solubilize insoluble phosphates, further contributing to plant growth.Aims
The objectives of this study were the following: isolate, select, and identify nodulating bacteria in the cowpea that are efficient not only in biological nitrogen fixation (BNF) but also in the solubilization of insoluble inorganic phosphates; identify and quantify the organic acids produced; and establish the relationship between those acids and the solubilizing capacity.Methods
The bacteria were captured from two soils containing high concentrations of insoluble phosphorus from the cities of Lavras and Patos de Minas, using the cowpea [Vigna unguiculata (L.) Walp.] as bait. We obtained 78 strains, which were characterized according to their cultural attributes in culture medium 79 with the strains UFLA 03-84, INPA 03-11B, and BR3267 (approved by the Ministry of Livestock and Supply Agriculture—MAPA, as inoculants for the cowpea) and Burkholderia cepacia (LMG1222T), which was used as a positive control for phosphate solubilization. Strains that were selected for their efficiency in both processes were identified by 16S rDNA sequence analysis. We evaluated the symbiotic efficiency (BNF) in a greenhouse and the solubilization efficiency of CaHPO4, Al(H2PO4)3, and FePO4.2H2O in solid and liquid GELP media. Strains that excelled at the solubilization of these phosphate sources were also evaluated for the production of the following organic acids: oxalic, citric, gluconic, lactic, succinic, and propionic.Results
The presence of Acinetobacter, Bacillus, Firmicutes, Microbacterium, Paenibacillus, and Rhizobium was detected by 16S rDNA sequencing and analysis. Bacterial strains obtained from cowpea nodules varied greatly in the efficiency of their BNF and phosphate solubilization processes, especially in the strains UFLA 03-09, UFLA 03-10, UFLA 03-12, and UFLA 03-13, which were more efficient in both processes. More strains were able to solubilize insoluble inorganic calcium and iron phosphates in liquid medium than in solid medium. The production of organic acids was related to the solubilization of CaHPO4 and FePO4.2H2O for some strains, and the type and concentration of the acid influenced this process.Conclusions
These are the first results obtained with bacterial isolates from tropical soils in which the production of organic acids was detected and quantified to examine the solubilization of insoluble inorganic phosphates. 相似文献44.
45.
46.
Comparison of Penicillium echinulatum and Trichoderma reesei cellulases in relation to their activity against various cellulosic substrates 总被引:2,自引:0,他引:2
Penicillium echinulatum has been identified as a potential cellulase producer for bioconversion processes but its cellulase system has never been investigated in detail. In this work, the volumetric activities of P. echinulatum cellulases were determined against filter paper (0.27 U/mL), carboxymethylcellulose (1.53 U/mL), hydroxyethylcellulose (4.68 U/mL), birchwood xylan (3.16 U/mL), oat spelt xylan (3.29 U/mL), Sigmacell type 50 (0.10 U/mL), cellobiose (0.19 U/mL), and p-nitrophenyl-glucopiranoside (0.31 U/mL). These values were then expressed in relation to the amount of protein and compared those of Trichoderma reesei cellulases (Celluclast 1.5L FG, Novozymes). Both enzyme complexes were shown to have similar total cellulase and xylanase activities. Analysis of substrate hydrolysates demonstrated that P. echinulatum enzymes have higher beta-glucosidase activity than Celluclast 1.5L FG, while the latter appears to have greater cellobiohydrolase activity. Unlike Celluclast 1.5L FG, P. echinulatum cellulases had enough beta-glucosidase activity to remove most of the cellobiose produced in hydrolysis experiments. However, Celluclast 1.5L FG became more powerful than P. echinulatum cellulases when supplemented with exogenous beta-glucosidase activity (Novozym 188). Both cellulase complexes displayed the same influence over the degree of polymerization of cellulose, revealing that hydrolyzes were carried out under the typical endo-exo synergism of fungal enzymes. 相似文献
47.
Ana Sofia Cerquido Martin Vojtek Rita Ribeiro-Oliveira Salom Gonalves-Monteiro Maria Joo Barroca Aida Moreira da Silva Olga Viegas Victor Freitas Joana Beatriz Sousa Isabel M. P. L. V. O. Ferreira Carmen Diniz 《Current issues in molecular biology》2022,44(8):3598
Corema (C.) album is a shrub endemic to the Atlantic coast and has been described as yielding beneficial effects for human health. Nevertheless, studies concerning the bioactivity of C. album leaves are scarce. This study aims at investigating the anticancer potential and mode of action, of an hydroethanolic extract of C. album leaves (ECAL) on triple-negative breast cancer. This is a poor survival breast cancer subtype, owing to its high risk of distant reappearance, metastasis rates and the probability of relapse. The ECAL ability to prevent tumor progression through (i) the inhibition of cell proliferation (cell viability); (ii) the induction of apoptosis (morphological changes, TUNEL assay, caspase-3 cleaved) and (iii) the induction of DNA damage (PARP1 and γH2AX) with (iv) the involvement of NF-κB and of ERK1/2 pathways (AlphaScreen assay) was evaluated. ECAL activated the apoptotic pathway (through caspase-3) along with the inhibition of ERK and NF-κB pathways causing DNA damage and cell death. The large polyphenolic content of ECAL was presumed to be accountable for these effects. The extract of C. album leaves can target multiple pathways and, thus, can block more than one possible means of disease progression, evidencing the anticancer therapeutic potential from a plant source. 相似文献
48.
49.
Background
Although capable to evolve, viruses are generally considered non-living entities because they are acellular and devoid of metabolism. However, the recent publication of the genome sequence of the Mimivirus, a giant virus that parasitises amoebas, strengthened the idea that viruses should be included in the tree of life. In fact, the first phylogenetic analyses of a few Mimivirus genes that are also present in cellular lineages suggested that it could define an independent branch in the tree of life in addition to the three domains, Bacteria, Archaea and Eucarya. 相似文献50.
Luiz Henrique Soares de Andrade Wilson Max Almeida Monteiro de Moraes Eduardo Hiroshi Matsuo Junior Elizabeth de Orleans Carvalho de Moura Hanna Karen Moreira Antunes Jairo Montemor Ednei Luiz Antonio Danilo Sales Bocalini Andrey Jorge Serra Paulo José Ferreira Tucci Patricia Chakur Brum Alessandra Medeiros 《Molecular and cellular biochemistry》2015,402(1-2):193-202